Why does my rt2’s teach and Speedo needles jump all over the place. Speedo will jump 15mph. Do I need to lube the cables? 

Be carefully lubing cables, just wipe a very light smear of grease along the inner. RT2 in my opinion had a problem that year in that they forgot to add damping to the needle part so it goes wild. Be sure also that it's mounted as insulated as you can on the base. Also check the cable drive bit on the base is straight & not tweaked or pulled a bit from a cable running out of free movement when bars are turned fully.